Credit: ESA/DLR/Freie Universitat Berlin (G. Neukum)
Key Takeaways:
- A recent study examining Martian craters identified that the planet experienced multiple ice ages between approximately 640 and 98 million years ago.
- This research revealed a consistent pattern wherein the amount of remaining ice diminished with each successive ice age cycle, indicating a gradual desiccation of Mars.
- The observed ice ages were attributed to significant shifts in Mars's axial tilt (obliquity), with evidence derived from high-resolution orbiter images of glacial landforms correlated with climate models.
- The findings offer critical insights for future robotic and crewed missions by identifying potential long-lived ice deposits that could serve as resource-rich locations.
One of the big questions about Mars is how wet was it in the past, and why is it so dry today? A new study published online September 2, 2025, in the journal Geology, examined a number of martian craters. Scientists were looking for past ice deposits, which act like archives where the planet’s geological history can be studied. They found that Mars went through many ice ages during a period ranging from approximately 640 million to 98 million years ago. Interestingly, with each cycle, the amount of remaining ice decreased.
The study was led by Associate Professor Trishit Ruj from Institute for Planetary Materials, Okayama University, Japan, along with Hanaya Okuda from Kochi Institute for Core Sample Research, Japan, Hitoshi Hasegawa from Kochi University, Japan, and Tomohiro Usui from Institute of Space and Astronautical Science, Japan. The team studiedlandforms created by glaciers and preserved in craters between 20° and 45° north latitude.
In the press release, Ruj said, “Mars went through repeated ice ages, but the amount of ice deposited in craters steadily shrank over time. These icy ‘time capsules’ not only reveal how Mars lost its water but also mark places where future explorers might tap into hidden ice resources.”
Looking at pictures
The researchers’ data came from high-resolution images from NASA’s Mars Reconnaissance Orbiter. Of particular interest were any craters that showed signs of previous glaciers: ridges, moraines (piles of debris left behind by glaciers), and brain terrain (a pitted surface formed by ice-rich landforms). They then compared the shapes and orientations of these features with climate models. What they discovered was that ice lasted longer in the colder, shadowed southwestern walls of craters.
The results show that Mars endured many ice ages driven by shifts in the tilt (obliquity) of its axis. Earth’s axis also tilts, but Mars’ tilt changes a lot over millions of years. Because a planet’s tilt determines where sunlight lands most directly on its surface, Mars went through ages where icy regions grew and other ages where it melted. The team discovered that each cycle stored less ice, and the Red Planet gradually dried.
Related: How carbon dioxide glaciers gave Mars liquid water
Important for future missions
The findings could be important for future missions to Mars. Astronauts with access to buried ice could use it to make drinking water, breathable oxygen, and, potentially, rocket fuel. So, future missions wouldn’t have to haul these supplies with them.
“Knowledge of long-lived ice deposits helps identify safe and resource-rich regions for future robotic and crewed landings,” said Usui.
This study represents an important step toward unlocking the resources humans will need to survive on Mars.
